[Bug target/96933] rs6000: inefficient code for char/short vec CTOR

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=96933

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
very likely the byte stores and then the following vector load will also
trigger
STLF issues.